Retractable snout for metallic coating process and apparatus

ABSTRACT

Snout for metallic coating line extending from the strip preparation furnace to the coating metal bath, having a gas impermeable flexible joint permitting movement of the snout from a position with one end immersed in the coating bath to a position thereabove, permitting a change in coating metal bath or coating metal bath and container without degassing the strip preparation furnace.

United States Patent inventors Appl. No, Filed Patented AuigneeRETRACTABLE SHOUT FOR METALLIC COATING PROCESS AND APPARATUS 12 Claims,5 Drawing Figs.

u.s. C1. 118/65, 118/419, l18/423,118/503,277/135 lnt.C1. B051: 11/12Pleldolsenrcli 118/423- Primary Examiner- Morris Kaplan Anorney--Melville, Strasser, Foster and l-lofi'm an ABSTRACT: Snout for metalliccoating line extending from the strip preparation furnace to the coatingmetal bath, having a gas impermeable flexible joint permitting movementof the snout from a position with one end immersed in the coating bathto a position thereabove, permitting a change in coating metal bath orcoating metal bath and container without degassing the strip preparationfurnace.

PATENTEDJUUBISYI 3,592,160

SHEET 1 OF 2 F lG-l FIG-2 lNVENTOR/S ROMAN A. SCHWIETERMAN 8 KASIMIROGANOWSKI,

BY 44;; gwgzw ATTOR NEYS PATENTEU JULIBISYS 3,592 160 SHEET 2 BF 2INVENTORES ROMAN A. SCHWIETERMAN 8| KASIMIR OGANOWSKI,

ATTORNEYS RETRACTABLE SNOUT FOR METALLIC COATING PROCESS AND APPARATUSCROSS REFERENCE TO RELATED APPLICATION This is a division of applicationSer. No. 859,033 filed Sept. l8, I969 in the names of Schwieterman andOganowski, now U.S. Letters Patent No.

BACKGROUND OF THE INVENTION This application relates to a continuousmetallic coating operation wherein a ferrous base metal strand isconducted through a strip preparation furnace, and then, in a protectiveatmosphere through a down turned snout into a bath of molten coatingmetal. Exemplary commercial procedures now in widespread commercial useare described in U.S. Pat. Nos. 3,320,085 in the name of Turner and3,396,95l in the name of Cope et a]. The former contemplates a strippreparation furnace utilizing carefully controlled temperatures andfurnace atmospheres to achieve nonoxidizing surface cleaning by gas. Thelatter, while particularly directed to a procedure for preventingexcessive strip oxidation during line stops, describes a modification ofthe so-called Sendzimir process, wherein the surface of the strip isprepared to receive a molten metal coating by successive heat treatmentin an oxidizing and then a reducing atmosphere.

In either case, a down turned snout is provided at the end of the strippreparation furnace, one end of which is normally disposed beneath thesurface of the molten coating metal. This snout serves to maintain aprotective atmosphere about the cleaned strip until it comes intocontact with the coating metal.

This invention is directed primarily to the problem of changing a givencoating line from one metallic coating metal to another by changing thebath and/or container. Reference is made to U.S. Pat. No. 3,130,068 inthe name of Whitley which describes in detail many of the problemsassociated with the changeover in coating metals. According to thispatent, the changeover is accomplished by rapidly pumping the coatingmetal out of the coating pot and into a holding pot, removing thecoating machine (pot roll and finishing rolls) and coating pot, placinga new coating pot in position, and finally pumping the new coating metalinto the new pot.

In addition, as explained in that patent, the heating furnace and downturned snout are normally filled with a reducing gas, such as hydrogen.During the course of the coating metal changeover, the entire furnacehas to be degassed to eliminate the danger of explosion when the lowerend of the snout is no longer immersed in the coating metal.

SUMMARY OF THE INVENTION The instant invention, in its broadest aspect,contemplates a gas impermeable flexible joint associated with the downturned snout and permitting movement of the snout from the positionwherein its lower end is immersed in the coating metal bath to aposition thereabove.

The gas impermeable, flexible joint just referred to can take manyspecific forms, two of which are described in more detail hereinafter.

Once the coating machine is removed in a conventional manner, the snoutis raised to a position above the coating pot, and the strip can bedrawn up snugly against the lower end of the snout, which of coursemeans that the entire strip will be above the top of the coating pot.This will permit the original coating pot to be moved horizontally outof position, and a new pot moved into position.

The invention also contemplates the provision of a pair of battlesmounted within the snout, these baffles preferably being movable to aposition substantially closing the open end of the snout so thatdegassing of the entire strip preparation furnace can be eliminated.

DESCRIPTION OF THE FIGURES FIG. 1 is a schematic view of the end of acontinuous coating apparatus including the down turned snout and thecoating pot in the normal operating position.

FIG. 2 is a schematic diagram similar to FIG. 1 showing the snout in theretracted position.

FIG. 3 is a schematic diagram of the end of a coating apparatus showinga modified snout arrangement in the normal operating position.

FIG. 4 is a schematic diagram similar to FIG. 3 showing the snout in theraised position.

FIG. Sis a schematic diagram showing a modified liquid seal retractablejoint.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, theend of a conventional strip preparation furnace is indicated at 10, andthe strip being coated is shown at 12. It will be seen that securelyfixed to the end of the furnace I0 is the down turned snout indicatedgenerally at 14. It will be observed that the lowermost end of the snoutis immersed below the surface 16 of molten coating metal contained inthe pot 18.

The strip 12 passes through the furnace 10, over the turn down roll 20,through the snout I4, and into the bath of coating metal. It then passesunder the pot roll 22 submerged in the bath and emerges from the bath ina generally vertical path of travel. It will of course be understoodthat suitable apparatus will be provided for finishing the moltencoating metal as the strand emerges. Such apparatus might include exitrolls, jet nozzles, or the like, all of which are now known in the art.

The snout 14 shown in FIG. I includes the fixed portion 24 which issecured to the strip preparation furnace l0, and the retractable portion26. The joint between these portions has several very importantrequirements. According to this invention, it must be flexible orretractable so that the portion 26 of the snout is movable from thenormal operating position immersed in the coating metal to the positionshown in FIG. 2 wherein it is spaced above the coating pot. In addition,the joint must be gas impermeable.

That is, as explained earlier, the strip preparation furnace l0 andsnout I4 will be charged with a reducing gas such as hydrogen. Thesereducing gases will be introduced into the apparatus in the region ofthe snout and travel countercurrent to the strip through the strippreparation furnace. In order to eliminate the risk of fire andexplosion, it is most important that the flexible joint between thefixed portion 24 and the retractable portion 26 of the snout be gasimpermeable.

In the embodiment shown in FIGS. I and 2, the gas impermeable, flexiblejoint is formed by providing the annular cavity 28 around the upper endof the retractable portion 26 of the snout. This annular cavitycontains, at its bottom, heating means indicated schematically at 30,and is adapted to be filled with a low melting point metal or alloyhaving little tendency to vaporize at coating temperatures. Since somevaporization may occur, the metal or alloy selected should be one whichwill not adversely affect the molten metallic coating. Lead and thealloy Woods Metal are exemplary of those which may be used with success.The lower or free end of the fixed portion 24 of the snout is receivedin the annular cavity and immersed below the surface of the moltenliquid carried by the cavity.

It should therefore be apparent that relative movement between theportions 24 and 26 of the snout can be accomplished, and the joint willbe gas impermeable so long as the lower edge of the fixed portion 24 isbelow the surface of liquid in the cavity 28.

It will of course be understood that suitable means will be provided forraising the retractable portion 26 of the snout from the position shownin FIG. 1 to the position shown in FIG. 2. Such lifting means may takeany desired form, and do not, per se, form a part of this invention.

In order to change coating pots with the apparatus just described, thestrip would be stopped, the coating equipment including the pot roll 22and the finishing apparatus would be removed, the retractable portion 26will be moved upward to the position shown in FIG. 2, the strip will bepulled out ofthe bath and into a snug position about the retractedsnout, the original coating pot moved horizontally out of the way, andthe new coating pot moved into position. The above steps are thenreversed and the coating operation with a new or different coating metalmay be commenced.

It will be apparent to the skilled worker in the art that once thelowermost end of the snout is taken out of the coating metal bath, itwill be possible for air to enter the snout and strip preparationfurnace. The existence of the hydrogen or other reducing gas in thesecomponents at elevated temperatures presents a great risk of explosion,and hence the prior art has always found it necessary to degas thefurnace before the seal between the snout and the bath is broken. Thisdegassing may be accomplished by shutting off the supply of reducinggas, opening an auxiliary port, and burning the reducing gases as theyissue from the port. Alternatively, the furnace can be degassed bypurging with nitrogen or some other inert gas.

As seen in FIGS. l and 2, the snout 14 includes the pivotally mountedbaffles 32 and 34. It will be seen that these baffles are each pivotallymovable from the position shown in FIG. 1 wherein free passage of thestrip 12 is permitted, to the position shown in FIG. 2 wherein thesebaffles in effect clamp the strip being coated against a sidewall of thesnout. By means of these baffles, it is possible to eliminate the stepof degassing the furnace.

When these baffles are provided, the upper baffle 32 is closed andnitrogen or other inert gas is introduced into the snout in the regionbetween the baffles. An auxiliary port may be provided between thebaffles to burn out the gases therein. The lower baffle 34 is thenclosed. The inert purging gas is continued in the region between thebaffles at a pressure higher than that of the furnace in order to insurethat any leakage is into the furnace and not the other wayv At thistime, the lower end of the retractable portion 26 of the snout can heraised from the coating metal bath. The higher pressure region betweenthe baffles again insures that any gas flow is out of the snout and notthe other way. In other words, this higher pressure region preventsmixing of the reducing gas in the furnace l and atmosphere via the openend of the snout portion 26, thereby eliminating the hazard ofexplosion.

The concept of utilizing two baffles and a supply ofinert gastherebetween does not depend on the pivotal baffles shown. The inventionmay be practiced by utilizing two restrictive baffles in the snout and asufficient supply of inert gas to insure that there is no leakage out ofthe strip preparation furnace.

Since the lowermost end of the retractable portion 26 of the snout hasbeen immersed in the coating metal, it may be necessary to change thisportion of the snout when changing coating metal pots to avoidcontamination of the coating metal. This may be accomplished by severingthe strip adjacent the lower end of the retractable portion 26 of thesnout, and simply removing this portion of the snout. When a new portion26 is in place, the strip can be welded together at the severed point,and the operation can be continued.

FIGS. 3 and 4 illustrate diagrammatically a slightly differentembodiment of this invention. As seen in these figures, a gasimpermeable flexible bellows joint 44 is provided adjacent the end ofthe snout which is secured to the reducing furnace 10. A joint of thischaracter will permit pivotal motion at this point, thereby in turnpermitting the lower end of the snout to be raised upwards out of thecoating metal pot.

The baffle construction according to this embodiment is substantiallythe same as that shown in H08. 1 and 2, and has been identified withsimilar reference numerals.

While not shown in the drawings, it will be apparent that the lower endof the snout (that portion immersed in the coating pot) may be formed asa separate element, suitably joined to the remainder of the snout inorder to facilitate its removal when changing coating metal. In thisevent, the change can be accomplished as indicated earlier. That is, thestrip can be severed and the lowermost portion of the snout removed, orthe lowermost portion can be formed in two halves which may be removedwithout severing the strip.

FIG. 5 schematically illustrates an alternative form of a retractable,gas impermeable joint utilizing a liquid seal. According to thisembodiment, the annular molten liquid containlng cavity 46 is formed asa separate unit. The upper end of the retractable portion 26 of thesnout (shown in the raised position), and the lower end of the fixedportion 24 of the snout are provided with the mating sealing flanges 48and 50 respectively, each of which are immersed in the liquid containedin the cavity 46. This embodiment has the advantage that when changingsnouts, the annular cavity 46 need not be emptied ofits molten sealingmetal.

it is believed that the foregoing constitutes a full and completedisclosure of this invention. arious modifications can be made withoutdeparting from its scope and spirit.

The embodiments of the invention in which an exclusive property orprivilege we claim are defined as follows:

1. In apparatus for coating a strand with a molten coating metalincluding heating means arranged for the passage of said strandtherethrough, a bath of molten coating metal, and a snout secured tosaid heating means and having a portion normally immersed in said bath,the improvement which comprises: means associated with said snout andpermitting movement of said portion of said snout from said positionnormally immersed in said bath to a position thereabove, restrictivebaffle means adjacent each end of said snout, and means including asupply of inert gas under pressure intermediate said baffle means foreliminating explosive gasses therefrom.

2. The improvement claimed in claim 1, wherein said baffle means ismovable from an inoperative position permitting sub stantiallyunrestricted passage of said strand thereby to a sealing position.

3. The improvement claimed in claim 2 wherein said sealing position ofsaid baffle means is effective to force said strand against a side ofsaid snout.

4. ln apparatus for coating a ferrous strand with a molten coating metalincluding heating means, a bath of molten coating metal, and means formoving said strand in succession through said heating means and bath,the improved apparatus comprising:

a. a snout arranged for the passage of said strand therethrough fromsaid heating means to said bath, said snout having a first portionsecured to said heating means and a second portion normally immersed insaid bath, and including a gas impervious joint between said first andsecond portions;

b. roll means in said bath about which said strand passes, said rollmeans being spaced from the portion of said snout immersed in said bath;

c. means for moving said second portion of said snout with respect tosaid first portion to a position spaced above said bath; and

d. means operative when said roll means is removed, to

draw said strand against the free end of said second portion to aposition above said bath so that said bath of mol ten coating metal canbe changed.

5. The improved apparatus claimed in claim 4 wherein said gasimpermeable joint comprises a liquid seal joint.

6. The improved apparatus claimed in claim 4 wherein said gasimpermeable joint comprises a liquid filled annular container meansassociated with said second portion of said snout; and annular meansassociated with said first portion and received in said liquid filledcontainer means.

7. The improved apparatus claimed in claim 6 including heating meansassociated with said annular container means.

8. The improved apparatus claimed in claim 4 including spaced apartbaffle means disposed within said snout.

means is movable from an inoperative position permitting substantiallyunrestricted passage of said strand thereby to a sealing position.

12. The improvement claimed in claim ll wherein said sealing position ofsaid baffle means is effective to force said strand against a side ofsaid snout.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 59Dated y 13 J 97 Invenwfls) Roman A. Schwieterman; Kasimir Oganowski Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 9, following the phrase" U.S. Letters Patent No. insert3,551,185

Signed and sealed this 7th day of March. 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. Attesting Officer ROBERT GOTTSCHALKCommissionerof Patents RM PO-1050 1 USCOMM-DC 60376-F69 fl- U75.GOVERNMENY PRINTING OFFICE L 1989 0-366-331

1. In apparatus for coating a strand with a molten coating metalincluding heating means arranged for the passage of said strandtherethrough, a bath of molten coating metal, and a snout secured tosaid heating means and having a portion normally immersed in said bath,the improvement which comprises: means associated with said snout andpermitting movement of said portion of said snout from said positionnormally immersed in said bath to a position thereabove, restrictivebaffle means adjacent each end of said snout, and means including asupply of inert gas under pressure intermediate said baffle means foreliminating explosive gasses therefrom.
 2. The improvement claimed inclaim 1, wherein said baffle means is movable from an inoperativeposition permitting substantially unrestricted passage of said strandthereby to a sealing position.
 3. The improvement claimed in claim 2wherein said sealing position of said baffle means is effective to forcesaid strand against a side of said snout.
 4. In apparatus for coating aferrous strand with a molten coating metal including heating means, abath of molten coating metal, and means for moving said strand insuccession through said heating means and bath, the improved apparatuscomprising: a. a snout arranged for the passage of said strandtherethrough from said heating means to said bath, said snout having afirst portion secured to said heating means and a second portionnormally immersed in said bath, and including a gas impervious jointbetween said first and sEcond portions; b. roll means in said bath aboutwhich said strand passes, said roll means being spaced from the portionof said snout immersed in said bath; c. means for moving said secondportion of said snout with respect to said first portion to a positionspaced above said bath; and d. means operative when said roll means isremoved, to draw said strand against the free end of said second portionto a position above said bath so that said bath of molten coating metalcan be changed.
 5. The improved apparatus claimed in claim 4 whereinsaid gas impermeable joint comprises a liquid seal joint.
 6. Theimproved apparatus claimed in claim 4 wherein said gas impermeable jointcomprises a liquid filled annular container means associated with saidsecond portion of said snout; and annular means associated with saidfirst portion and received in said liquid filled container means.
 7. Theimproved apparatus claimed in claim 6 including heating means associatedwith said annular container means.
 8. The improved apparatus claimed inclaim 4 including spaced apart baffle means disposed within said snout.9. The improvement claimed in claim 8 including means intermediate saidbaffle means for eliminating explosive gases therefrom.
 10. Theimprovement claimed in claim 9 wherein said means intermediate saidbaffles is a supply of inert gas under pressure.
 11. The improvementclaimed in claim 8 wherein said baffle means is movable from aninoperative position permitting substantially unrestricted passage ofsaid strand thereby to a sealing position.
 12. The improvement claimedin claim 11 wherein said sealing position of said baffle means iseffective to force said strand against a side of said snout.